A spark plug of an internal combustion engine may become fouled via wet fuel, carbon deposits, or fuel additives. The spark plug includes a center electrode that is surrounded by a ceramic insulator, except at the tip of the spark plug where the center electrode is exposed and proximate to a ground electrode that is part of the spark plug casing. The fuel and deposits may make the ceramic insulator conductive so that spark is not initiated in the gap between the center electrode and the ground electrode. Rather, the spark plug may discharge in a crevice volume that is located between the ceramic insulator and the spark plug casing. This type of discharge may be described as a rim fire and a rim fire spark event may lead to late burning of gases in the cylinder or a misfire. Late burns and misfires may reduce engine power and increase engine emissions. Therefore, it may be desirable to provide a way of identifying rim firing events and mitigate the possibility of additional rim firing events.
The inventors herein have recognized the above-mentioned disadvantages and have developed a spark plug monitoring system, comprising: an engine with an ignition coil including a primary coil; and a controller including executable instructions stored in non-transitory memory to integrate a voltage of the primary coil beginning a first predetermined time after the ignition coil begins to discharge to a second predetermined time after the ignition coil begins to discharge, and instructions to adjust operation of the engine responsive to the integration via the controller.
By monitoring a voltage of a primary ignition coil, it may be possible to provide the technical result of determining the presence or absence of a rim firing spark plug. In particular, once discharge of a secondary coil that is magnetically coupled to the primary ignition coil begins, a voltage of the primary coil may be integrated and the value of the integration may be indicative of the presence or absence of rim firing of a spark plug. If rim firing is indicated, the engine may be operated at a higher load and/or with a leaner air-fuel mixture to reduce the possibility of further rim firing events.
The present description may provide several advantages. In particular, the approach detects spark plug rim firing in an unobtrusive way so that engine operation may not be influenced by the monitoring. In addition, the approach may detect rim firing via a voltage slope, voltage level, or integrated voltage value so that processing power of the engine controller may be matched to the method of monitoring the spark plug. Further, the approach provides for actions to reduce the possibility of further spark plug rim firing events so as to improve engine operation.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.